Preeclampsia is a hypertensive disorder that occurs only during pregnancy, affecting roughly 5% of all pregnancies. Preeclampsia typically arises after 20 weeks gestation (middle to late pregnancy). It is a rapidly progressive condition characterized by high blood pressure and abnormally high concentrations of protein in the urine. Preeclampsia and other hypertensive disorders of pregnancy are a leading cause of maternal and infant illness and death. By conservative estimates, these disorders are responsible for 76,000 maternal and 500,000 infant deaths each year. The etiology and pathogenesis of preeclampsia remains poorly understood and useful predictors of the disease are currently lacking (Roberts and Hubel, Lancet, 354:788-789, 1999).
This disease, or the threat of onset, is the most common cause of elective premature delivery, accounting for approximately 15% of all premature births. The measurement of blood pressure and testing for proteinuria in all pregnant women is carried out predominantly for the detection of preeclampsia. However, these procedures and the care of affected women and of the premature children make considerable demands on healthcare resources. In addition, there is no widely accepted or accurate method for the early prediction of preeclampsia. Elevation of the blood pressure and detection of protein in the urine occur when the disease process is well established.
Detection of an abnormality of the blood flow to the uterine artery by Doppler ultrasound in women who later develop preeclampsia has been of some predictive use but this abnormality has been found to be relatively non-specific. In addition, both sFlt-1 and soluble endoglin were proposed to have potential predictive utility for preeclampsia, but their modest screening performance (sensitivity for detection of impending preeclamptic cases) suggests that while they may not be clinically useful as sole/individual disease predictors. Thus, a need remains for the development of an early pregnancy predictive test for preeclampsia and resultant eclampsia.